In recent years, various types of camera devices equipped with a camera element such as a CCD and CMOS and others have been widely used. Along with the development of miniature and high performance camera elements, the small-sized camera lenses with good optical properties and bright Fno are needed.
The technology related to the camera lens composed of four small-sized lenses with good optical properties and bright Fno is being developed gradually. The camera lens is composed of four lenses, which are lined up from an object side in an order as follows: a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power and a fourth lens having a negative refractive power.
The camera lens disclosed in the embodiments of Patent Document 1 (as listed below) is the above-described camera lens constituted of four lenses. However, since the shapes of the second and fourth lenses are not sufficient, the brightness of Fno≥2.4 is not sufficient.
The camera lens disclosed in the embodiments of Patent Document 2 (as listed below) is the above-described camera lens constituted of four lenses. However, since the refractive power distribution of the fourth lens is not sufficient, the brightness of Fno2.4 is not sufficient.